A preliminary study on the use of mannan oligosaccharides (MOS) in freshwater crayfish, Astacus leptodactylus Eschscholtz, 1823 juvenile diets

Abstract

The effects of dietary mannan oligosaccharides (MOS) on the survival and growth of Astacus leptodactylus juveniles were evaluated. Experimental diets were prepared by using supplementation of 0 (Control), 1.5, 3.0, and 4.5 g MOS kg(-1) commercial trout larvae diet containing 43 g kg(-1) protein and 15.74 g kg(-1) lipid. A. leptodactylus juvenile with an average total length of 3.6 +/- 0.46 cm (TL) and average weight of 1.25 +/- 0.43 g was stocked in 0.2-m(2) aquariums at a rate of 50 crayfish/m(2) and reared for 60 days at 22.8 degrees C. The experiment consisted of four treatments with three replicates each. Each aquarium contained ten crayfish. Crayfish juvenile fed with 0, 1.5, 3.0, and 4.5 MOS attained 6.15 +/- 0.49, 5.94 +/- 0.29, 7.34 +/- 0.39, and 5.94 +/- 0.27 cm final total length and 50, 56.67, 46.67, and 50% survival rates, respectively. Moreover, molting frequencies in 0, 1.5, 3.0, and 4.5 g kg(-1) MOS groups were detected as 44.44, 61.11, 83.33, and 38.88%, respectively. At the end of the experiment, a general enhanced growth performance (P 0.05) in percentage moisture, protein, and ash (wet-weight basis) in the tail meat of A. leptodactylus juvenile among treatments (diet) that averaged 82.3, 16.1, and 1.2%, respectively. However, lipid value was significantly different among the diets P < 0.05), with values between 0.13 and 0.32. From the current results, it could be advised to use MOS at the rate of 3.0 g kg(-1) in A. leptodactylus juvenile diets